Spiral stitching mechanism



April 13, 1965 E. A. TOBIAS ETAL 3,177,831

SPIRAL STITCHING MECHANISM Filed Aug. 18, 1958 2 Sheets-Sheet l III/IIIIIIII I /IlllllllllIIIIIIIIIIIIII Inveh v ors Edward 7 651 03 WilliamKauman Sh hen J. Tobias ar 'i'ornejS April 1965 E. A. roams ETAL SPIRALSTITCHING' MECHANISM 2 Sheets Sheet 2 Filed Aug. 18, 1958 Fig. 4

INVENTORS EDWARD A. TOBIAS BY WILLIAM KAUFMAN STEPHEN J. TOBIAS ATTORNEYUnited States Patent 3,177,831 SPIRAL STITQEEWG MECHANEM Edward A.Tobim, 17 Monroe Place; William Kaufman, 575 King St.; and Stephen J.Tobias, 17 Monroe Place, all of Port Chester, N55.

Filed Aug. 18, 1958, Ser. No. 755,640 7 Claims. (Cl. 112-2) The presentinvention relates to sewing machines. More particularly, the presentinvention relates to a spiral stitching mechanism for sewing machines.

The spiral stitching mechanism of the present invention serves to stitchfabrics with a continuous spiral seam and is specifically adapted tostitch generally hemisphericallyconstructed forms of work such as, forexample, brassiere cups. The mechanism of the present invention servesto produce a spiraling continuous line of stitching on the hemisphericalcup which serves to reinforce and stiffen the cup.

The spiral stitching mechanism of the present invention is combined witha conventional sewing machine having stitching means, a work plateprovided with means adjacent said stitching means for pivotallysupporting a workpiece thereon, a work bar, means coupling said work barto said work plate in 'a manner whereby said workpiece is adapted to bemoved by said work bar laterally relative to the direction of forwardfeed produced by said stitching means and a source of power.

A conventional sewing machine may be facilely adapted to sew spiralseams on fabrics of various types and qualities by the utilization ofthe spiral stitching mechanism of the present invention. The spacingbetween the consecutive convolutions of the spiral seam sewn by themechanism of the present invention may be readily adjusted.

In accordance with the present invention, the spiral stitching mechanismeffects lateral movement of a workpiece relative to the stitchingmechanism at a varying rate thereby to produce spiral stitching, bytranslating the rotation of a shaft driven by the power source into suchlateral movement. The translation of the rotation of the power shaftinto a varying lateral motion is provided by a gear segment driven bythe power source and a connecting arm or loss bar pivoted on the gearsegment at one end and adapted to move freely along the edge of alateral pressure bar at the other end, the work bar being coupled tosaid other end of said loss bar.

The principal object of the present invention is to provide a spiralstitching mechanism for producing a spiral seam having uniformly spacedconsecutive convolutions.

An object of the invention is the provision of a spiral stitchingmechanism for producing a spiral seam having uniformly spacedconsecutive convolutions the spacing of which may be varied as desired.

Another object of the invention is the provision of a spiral stitchingmechanism which may be facilely installed in a conventional sewingmachine.

Another object of the invention is the provision of a spiral stitchingmechanism which may be readily installed in a conventional sewingmachine with no waste of space whatever.

Another object of the invention is the provision of a spiral stitchingmechanism which may be readily installed in a conventional sewingmachine in a manner whereby oil drippings from the machine are utilizedto lubricate the mechanism.

Another object of the invention is the provision of a spiral stitchingmechanism which is of relatively simple configuration. 7

Another object of the invention is the provision of a spiral stitchingmechanism which comprises relatively few parts.

3,177,831 Fatented Apr. 13 1965 ice Another object of the invention isthe provision of a spiral stitching mechanism which is of rugged anddurable construction.

Another object of the invention is the provision of a spiral stitchingmechanism which is instantly and easily retractable.

Still another object of the invention is the provision of a spiralstitching mechanism which is relatively inexpensive to manufacture andwhich costs virtually nothing to maintain. 7

These and other objects and features of the invention will be apparentfrom a consideration of the following detailed description taken inconnection with the accompanying drawing, wherein:

FIG. 1 is a schematic diagram, partly in section, of an embodiment ofthe spiral stitching mechanism of the present invention;

FIG. 2 is' a schematic diagram, partly in section, of a portion of theembodiment of the spinal stitching mechanism of FIG. 1, a portion ofFIG. 2 being taken along the line 22 of FIG. 1 and a FIG. 3 is aschematic diagram, partly in section, of

another portion of the embodiment of FIG. 1, a portion of FIG. 3 beingtaken along the line 3-3 of FIG. 1.

FIG. 4 is a detailed elevation view, partly in section, illustrating thecoupling of the work bar to the work plate of the mechanism.

In FIG. 1, the invention is illustrated in the form of a unit which maybe easily attached to a conventional sewing machine whereby suchmachine, without alteration or delay, may be readily converted to amachine for providing spiral stitching. The main elements of theinvention are supported in a housing 1 having a bottom portion 2 andsides 3, 4, 5 and 6. The housing '1 is preferably provided withfastening means for aflixing said housing to a sewing machine in placeof the conventionally used oil pan. Suitable fastening means maycomprise, for example, apertured ears 7, 8, 9 and 10 through which thehousing 1 may be fastened by screws to the under surface of a sewingmachine work surface in the area formerly occupied by the oil pan in amanner whereby said housing is supported in a substantilaly horizontalposition with the bottom portion 2 down.

A variable speed pulley 11 is driven by the power source of the machinein any suitable manner known in the art and rotates a shaft 12 to whichit is afiixed at a speed which may be varied by Variation of the speedof the power source in any suitable manner known in the art. s

The shaft 12 is connected in a gear box 13 to continuously drive amaster gear'(not shown). The gear b0x'13 comprises any suitable gearcoupling means known in the art for translating the rotary motionof theshaft 12 to a rotary motion of the master gear in aplane substantiallyperpendicular to the plane of rotation of said shaft.

A pinion 14 extends from the top of the gear box 13 and is adapted to bedriven by the master gear. When so driven, the pinion 14 rotates aboutits axis 15. The gear box 13 further comprises any suitable clutch meansknown in the art for driving the pinion 14 with the master gear whensaid clutch means is engaged and for permitting free rotation of saidpinion when said clutch means is disengaged. The clutch means includedin the gear box 13 is operated manually through a control rod (notshown) extending from said gear box. In the course of normal operationof the machine, the clutch is engaged and the pinion 14 is driven by themaster gear of the gearbox 13 to rotate about'its axis 15 at asubstantially constant speed. s, V

In a preferred embodiment of the invention, the gear 1:..3 box 13 is sopositioned in the bottom portion 2 of the housing 1 that the pinion 14is substantially parallel to said bottom portion in a substantiallyhorizontal plane which is located at a small distance above the saidbottom portion whereas the bulk of said gear box including the shaft 12and pulley 11 are located below the said bottom portion outside saidhousing.

The pinion 14 rotates about the axis 15 in the direction indicated by anarrow (1 'or pivoting element 16 in a manner'whereby it drives said gearsegment at a substantially constant rate in the direction indicated byan arrow b. The gear segment 16 is supported by a pivot pin 17 and isadapted to rotate about said pivot pin. That is, the gear segment 16describes a substantially arcuate motion. The pivot pin 17 (FIG. 2) isaffixed substantially vertically to the bottom portion 2 of the housing1 and supports the gear segment 16 in a substantially horizontal planelocated at a small distance above said bottom portion. The gear segmentor pivoting element 16 may be of any suitable configuration, of course;the form illustrated having been selected because it occupies a minimumof space.

A connecting arm or loss bar 18 is positioned in a substantiallyhorizontal plane slightly above the plane of the gear segment 16. Theloss bar 18 is pivotally coupled at one end to the upper surface of thegear segment 16 through a pivot pin 19 about which said loss bar isfreely rotatable.

The other end of the loss bar 18 is affixed to a plate 20 which ispreferably positioned below said loss bar in a manner whereby there isno interference between the gear segment 16 and said plate at anyposition of either. A ball bearing 21 is aflixed to the plate 20 in amanner whereby it is freely rotatable about its axis 22. The ballbearing 21 is adapted to roll dong a substantially lateral edge 23 of alateral pressure bar 24. The lateral pressure bar 24 is affixed to thebottom portion 2 of the housing 1 in a manner whereby said lateralpressure bar is positioned in a substantially horizontal plane at adistance above said bottom portion sufficient to permit the free'movernent of the gear segment 16 and the plate 20 between the bottomsurface of the said pressure bar and the upper surface of said bottomportion in any position of said gear segment and said plate. The lateralpressure bar 24 is positioned to present the edge 23 thereof in thelateral direction relative to the direction of forward feed produced bythe stitching means of the sewing machine as previously defined.

As a result of the unique coupling arrangement of the present inventionthe ball bearing 21 moves in a lateral direction along the edge '23 ofthe lateral pressure bar 24 indicated by an arrow 0 at a varying ratewhich is a maximum when said bearing is at its farthest right-hand andengages a gear segment position and which is a minimum when said bearingis p at its farthest left-hand position. The pivot 19 area of the lossbar 18 moves in a direction generally indicated by an arrow d.

In FIG. 2 a work bar 25, not shown in FIG. 1 to prevent complication of:the drawing and thereby aid in the clarity of the illustration, issupported by any suitable means known in the art for permitting freemovement thereof in a lateral direction relative to the direction offorward feed of the sewing machine, as previously described. Suitablesupporting means may comprise, for example, ball bearing [means 26 and27;the ball bearing means 26 being supported in an aperture in the side3 of the housing '1. Any suitable coupling means known in the art may beutilized to coupletthe work bar 25 to the loss bar 18 in a manner.whereby said work bar moves conjointly with the ball bearing 21.Suitable coupling means may comprise, for example, a pin 28' supportedon the plate 20 coaxially with the axis 22 of the ball bearing 21 andfitting in a substantially vertical aperture through the work bar 25. Ina preferred embodiment of the invention, the ball bearing 21 may becovered by a second plate 29 which is positioned parallel to the firstplate 29 and spaced from said first plate so that it may move freelyover the upper surface of the lateral pressure bar 24; the ball bearing21 being freely rotatable about its axis 22 and moving along the lateraledge 23 of said lateral pressure bar. The pin 28 may be afiixed to theupper plate 29 and fitted in a substantially vertical hole through thework bar 25. As seen in FIG. 4, the pin 28 is further secured to workplate 36. The work plate 36 is provided with a work-engaging needle 38upon which the brassiere cup C is mounted. A sewing machine 44) isadapted to perform the spiral stitching on the cup C.

The lateral motion at a varying rate of the work bar 25 may betranslated to thespiral stitching of a workpiece by any suitablecoupling means between said work bar and I the work plate of the sewingmachine known in the art. Such a structure for coupling the presentmechanism to a work plate of a sewing machine is clearly shown in our.co-pending US. patent application, Serial No. 635,215,

filed January 22, 1957, now Patent No. 2,955,551, and entitled SpiralStitching Device for Sewing Machines. The coupling of the work bar 25 tothe work plate ofthe machine is through a slot in the working surface ofthe machine since the spiral stitching mechanism of the presentinvention is positioned beneath said Working surface as previouslydescribed. Suitable work bar to work plate coupling means may comprise apivot pin coupling said work bar and workplate in a manner whereby theworkpiece, which may be pivoted on said work plate, is moved away fromthe stitching means of the sewing machine laterally relative to thedirection of forward feed produced by said stitching means at a varyingrate which decreases from an initial maximum value whereby a spiral seamis sewn in said workpiece.

The spiral seam produced by the mechanism of the present invention hasuniformly spaced consecutive convolutions due to the varying rate oflateral motion of the work bar 25. Thespacing of these convolutions maybe varied as desired by varying the speed of the pulley 11 by anysuitable means known in the art. Thus, at a relatively low pulley 11speed, the lateral motion of the work bar 25 varies at a relatively slowrate and the consecutive convolutions are relatively closely spaced;whereas, at a relatively high pulley 11 speed, the lateral motion of thework bar 25 varies at a relatively fast rate and the consecutiveconvolutions are relatively widely spaced. I The spiral stitchingmechanism of the present invention is instantly and easily retractibleby manual operation of the clutch control rod (not shown) extending fromthe gear box 13 to disengage the clutch. When the clutchis disengagedthe pinion 14 and the gear segment 16 are freely rotatable about theaxis 15 and pivot 19, re-

spectively, so that the work bar 25 may be manually returned to itsfarthest right-hand position thereby movmg the ball bearing 21 back toits farthest right-hand position and moving the. gear segment 16 to itsstart position. In the start position, the pivot pin 19 is at a maximumdistance from the wall 4 of the housing 1 and the pin 28 is at itsfarthest right-hand position at its maximum distance from the wall 3 ofsaid housing. When the clutch is engaged, the operation is instituted asdescribed. At the termination of the operation, before the disengagingof the clutch, when the mechanism is in its stop position, the pin 28,ball bearing 21 and work bar 25 are at "their farthest left-handpositions at a rninimurn distance from the wall 3 of the housing 1 andp1vot pin 19 is at a minimum distance from the wall 4 of said housing.

A suitable type ofclutch arrangement which may be utilized in the gearbox 13 may comprise, for example, a frictiontype clutch of the typeshown in FIG. 3, wherein the axis of the pinion 14 is the axis of theshaft 30. A driven gear 31 is affixed to the shaft 30 and is adapted torotate said shaft thereby to rotate the pinion 14,

, which is also aflixed to said shaft. A master drive gear 32 iscontinuously rotated about the axis 15 by the power source (not shown)through the pulley 11 by any suitable means known in the art. The masterdrive gear 32 is not affixed to the shaft 30 but may be affixed, forexample, to a shaft 33 which is coaxial with the shaft 30 and of adiameter which is sufiiciently larger than the diameter of said shaft 30to permit free rotation and axial movement of the said shaft 36.

When the clutch arrangement is engaged, the driven gear 31 is infricitonal engagement with the master drive gear 32 and rotates theshaft 3% and the pinion l4 atlixed to said shaft. To disengage theclutch, the manually operated control rod (not shown) extending from thegear box 13 is moved to disengage the driven gear 31 from the masterdrive gear 32. The disengagement of the gears 31 and 32 may beaccomplished by any suitable means known in the art for moving the shaft30 upward in the direction of an arrow e. When the shaft 30 is movedupward a suflicient distance in the direction of the arrow (2" thedriven gear 31 is moved out of frictional engagement with the masterdrive gear 32 and the pinion 14 and the gear segment 16 are freelyrotatable about the axis 15 and pivot 19, respectively; said driven gearbeing freely rotatable about said axis.

In accordance with another feature of the present invention, the clutcharrangement is automatically disengaged to prevent stripping of thegears in the event that the mechanism is permitted to run to itsmechanical limit. The automatic disengagement of the clutch thusfunctions as a safety stop for the spiral stitching mechanism of thepresent invention. The automatic safety stop comprises a substantiallywedge shaped member 34 aflixed to the gear segment 16 in a positionwhereby said member is adapted to engage the under surface of an annularhead 35 affixed substantially coaxially to the shaft 30. The member 34and the head 35 are so positioned that when the gear segment 16 nearsthe position that it acquires at the termination of the operation, andis moving in the direction of the arrow 11, the upper surface of themember 34 engages the under surface of the head 35. As the gear segment16 continues to move in the direction of the arrow 12 the member 34lifts the head 35, by reason of the inclined upper surface of saidmemher, and thereby moves the shaft 30 upward in the direction of thearrow e. The incline of the upper surface of the member 34 is sufficientto move the shaft 30 upward a distance sufiicient to disengage thedriven gear 31 from the master drive gear 32 and thereby disengage theclutch arrangement. This permits free rotation of the pinion 14, thedriven gear 31 and the gear segment 16 and prevents stripping of thegears of the gear box 13 and of said pinion and gear segment.

While the invention has been described by means of a specific exampleand in a specific embodiment, we do not wish to be limited thereto, forobvious modifications will occur to those skilled in the art withoutdeparting from the spirit and scope of the invention.

What we claim is:

1. The combination with a sewing machine having stitching means, a workplate provided with means adjacent said stitching means for pivotallysupporting a workpiece thereon, a work bar, means coupling said work barto said work plate in a manner whereby said workpiece is adapted to bemoved by said work bar laterally relative to the direction of forwardfeed produced by said stitching means and a source of power, of meansfor moving said work bar at a varying rate whereby said stitching meansproduces a seam in the form of a spiral in said workpiece, saidlast-mentioned means comprising a pivoting element, means for drivingsaid pivoting element from said source of power, said power sourceincluding clutch means for disengaging said driving of said pivotingelement thereby permitting free rotation of said pivoting'element, meansmounted on said pivoting element for automatically disengaging saidclutch means at a predetermined position of the said pivoting element, aloss bar pivotally coupled at one end to said pivoting element, meansguiding the other end of said loss bar in said lateral direction in amanner whereby said'other end of the said loss bar moves at a varyingrate in the said lateral direction, and means coupling said other end ofsaid loss bar to said work bar in a manner whereby the said work barmoves conjointly with the said other end of said loss bar.

2. The combination with a sewing machine having stitching means, a workplate provided with means adjacent said stitching means for pivotallysupporting a workpiece thereon, a work bar, means coupling said work barto said work plate in a manner whereby said workpiece is adapted to bemoved by said work bar laterally relative to the direction of forwardfeed produced by said stitching means, and a source of power, means formoving said work bar at a varying rate whereby said stitching meansproduces a seam in the form of a spiral in said workpiece, saidlast-mentioned means comprising a pivoting element, means for drivingsaid pivoting element at a substantially constant rate from said sourceof power, a loss bar pivotally coupled at one-end to said pivotingelement, means guiding the other end of said loss bar in said lateraldirection in a manner whereby said other end of the said loss bar movesat a varying rate in the said lateral direction, said rate decreasingfrom an initial maximum value, and means coupling said other end of saidloss bar to said work bar in a manner whereby the said work bar movesconjointly with the said other end of said loss bar.

3. The combination with a sewing machine having stitching means, a workplate provided with means adjacent said stitching means for pivotallysupporting a workpiece thereon, a work bar, means coupling said Work barto said work plate in a manner whereby said workpiece is adapted to bemoved by said work bar laterally relative to the direction of forwardfeed produced by said stitching means and a source of power, of meansfor moving said work bar at a varying rate whereby said stitching meansproduces a seam in the form of a spiral in said workpiece, saidlast-mentioned means comprising a gear segment, means for driving saidgear segment at a substantially constant rate from said source of power,a loss bar pivotally coupled at one end to said gear segment, a lateralpressure bar positioned whereby an edge thereof extends in said lateraldirection, means guiding the other end of said loss bar along said edgeof said pressure bar in a manner whereby said other end of the said lossbar moves at a varying rate in the said lateral direction, said ratedecreasing from an initial maximum value, and means coupling said otherend of said loss bar to said work bar in a manner whereby the said workbar moves conjointly with the said other end of said loss bar.

4. The combination with a sewing machine having stitching means, a workplate provided with means adjacent said stitching means for pivotallysupporting a workpiece thereon, a work bar, means coupling said work barto said work plate in a manner whereby said workpiece is adapted to bemoved by said work bar laterally relative to the direction of forwardfeed produced by said stitching means and a source of power, of meansfor moving said work bar at a varying rate whereby said stitching meansproduces a seam in the form of a spiral in said workpiece, saidlast-mentioned means comprising a gear segment, means for driving saidgear segment at a substantially constant rate from said source of power,a loss bar pivotally coupled at one end to said gear segment, a lateralpressure bar positioned to present an edge thereof in said lateraldirection, ball bearing means guiding the other end of said loss baralong said edge of said pressure bar in a manner whereby said other endof the 7 said loss bar moves at a varying rate in the said lateraldirection, said rate decreasing from an initial maximum value, and meanscoupling said other end of said loss bar to said Work bar in a mannerwhereby the said work bar moves conjointly with the said other end ofsaid loss bar.

5. The combination with a sewing machine having stitching means, a workplate provided with means adjacent said stitching means for pivotallysupporting a workpiece thereon, a work bar, means coupling said work barto said work plate in a manner whereby said workpiece is adapted to bemoved by said work bar laterally relative to the direction of forwardfeed produced by said stitching means, and a source of power, means formoving said work bar at a varying rate whereby said stitching meansproduces a seam in the form of a spiral in said workpiece, saidlast-mentioned means comprising pivoting element means for driving saidpivoting element at a substantially constant rate from said source ofpower, a loss bar pivotally coupled at one end to said pivoting element,a lateral pressure bar positioned whereby an edge thereof extends insaid lateral direction, ball bearing means guiding the other end of saidloss bar along said edge of said pressure bar in a manner whereby saidother end of said loss bar moves at a varying rate in the said lateraldirection, said rate decreasing from an initial maximum value, and meanspivotally coupling said other end of said loss bar to said work bar in amanner whereby the said work bar moves conjointly with the said otherend of said loss bar.

6. The combination with a sewing machine having stitching means, a Workplate provided with means adja cent said stitching means for pivotallysupporting a workpiece thereon, a work bar, means couplin said Work barto said work plate in a manner whereby said workpiece is adapted to bemoved by said work bar laterally relative to the direction of forwardfeed produced by said stitching means and a source of power, of meansfor moving said work bar at a varying rate whereby said stitching meansproduces a seam in the form of a spiral in said workpiece, saidlast-mentioned means comprising a gear segment, means for driving saidgear segment at a substantially constant rate from said source of power,a loss bar pivotally coupled at one end to said gear segment, a lateralpressure bar positioned to present an edge thereof 1 in said lateraldirection, ball bearing means supported at the other end of said lossbar guiding said other end of said lossbar along said edge of saidpressure bar in a manner whereby the said other end of said loss barmoves at a varying rate in the said lateral direction, said ratedecreasing from an initial maximum value, and means pivotally couplingsaid other end of said loss bar to said Work bar in a manner whereby thesaid work bar moves conjointly with the said other end of said loss bar,said last-mentioned means comprising a pin afi'ixed to said other end ofsaid loss bar substantially eoaxially with said ball bearing means andadapted to fit in an aperture through said work bar.

7. The combination with a sewing machine having stitching means, a workplate provided with means adjacent said stitching means for pivotallysupporting a workpiece thereon, a work bar, means coupling said work barto said work plate in a manner whereby said workpiece is adapted to bemoved by said work bar laterally relative to the direction offorwardfeed produced by said stitching means and a source of power, ofmeans for moving said work bar at a varying rate whereby said stitchingmeans produces a seam in the form of a spiral in said workpiece, saidlast-mentioned means comprising a gear segment, means for driving saidgear segment at a substantially constant rate from said source of power,said power source including a pinion for driving said gear segment andclutch means for disengaging said pinion from said gear segment therebypermitting free rotation of the said gear segment, means forautomatically disengaging said clutch means at a predetermined positionof said gear segment, said last-mentioned means comprising a head membercoaxially mounted on said pinion and a substantially wedge shaped membermounted on said gear segment and adapted to coact with said head memberto lift said pinion vertically out of engagement with the said gearsegment upon a predetermined transverse of said gear segment in onedirection, a loss bar pivotally coupled at one end to said gear segment,a lateral pressure bar positioned whereby an edge thereof extends insaid lateral direction, means supported at the other end or" said lossbar guiding said other end of said loss bar along said edge of saidpressure bar in a manner whereby the said other end of said loss barmoves at a varying rate in the said lateral direction, said ratedecreasing from an initial maximum value, and means pivotally couplingsaid other end of said loss bar to said work bar in a manner whereby thesaid Work bar moves conjointly with the said other end of said loss bar.

References Cited by the Examiner UNITED STATES PATENTS JORDAN FRANKLIN,Primary Examiner.

THOMAS HICKEY, DAVID J. WILLIAMOWSKY,

' Examiners.

1. THE COMBINATION WITH A SEWING MACHINE HAVING STITCHING MEANS, A WORKPLATE PROVIDED WITH MEANS ADJACENT SAID STITCHING MEANS FOR PIVOTALLYSUPPORTING A WORKPIECE THEREON, A WORK BAR, MEANS COUPLING SAID WORK BARTO SAID WORK PLATE IN A MANNER WHEREBY SAID WORKPIECE IS ADAPTED TO BEMOVED BY SAID WORK BAR LATERALLY RELATIVE TO THE DIRECTION OF FORWARDFEED PRODUCED BY SAID STITCHING MEANS AND A SOURCE OF POWER, OF MEANSFOR MOVING SAID WORK BAR AT A VARYING RATE WHEREBY SAID STITCHING MEANSPRODUCES A SEAM IN THE FORM OF A SPIRAL IN SAID WORKPIECE, SAIDLAST-MENTIONED MEANS COMPRISING A PIVOTING ELEMENT, MEANS FOR DRIVINGSAID PIVOTING ELEMENT FROM SAID SOURCE OF POWER, SAID POWER SOURCEINCLUDING CLUTCH MEANS FOR DISENGAGING SAID DRIVING OF SAID PIVOTINGELEMENT THEREBY PERMITTING FREE ROTATION OF SAID PIVOTING ELEMENT, MEANSMOUNTED ON SAID PIVOTING ELEMENT FOR AUTOMATICALLY DISENGAGING SAIDCLUTCH MEANS AT A PREDETERMINED POSITION OF THE SAID PIVOTING ELEMENT, ALOSS BAR PIVOTALLY COUPLED AT ONE END TO SAID PIVOTING ELEMENT, MEANSGUIDING THE OTHER END OF SAID LOSS BAR IN SAID LATERAL DIRECTION IN AMANNER WHEREBY SAID OTHER END OF THE SAID LOSS BAR MOVES AT A VARYINGRATE IN THE SAID LATERAL DIRECTION, AND MEANS COUPLING SAID OTHER END OFSAID LOSS BAR TO SAID WORK BAR IN A MANNER WHEREBY THE SAID WORK BARMOVES CONJOINTLY WITH THE SAID OTHER END OF SAID LOSS BAR.